the stories have it all wrong.
sirius never calls regulus a mama’s boy, because he isn’t. walburga doesn’t favor regulus. she favors neither of them. she is overbearing with sirius and absent at best with her second son, the dimmer star.
sirius is a mama’s boy. it is sirius who runs into a different mother’s arms and never lets her go. it is sirius who clings onto euphemia potter and sirius who shows all of his mothers worst traits, her quintessential Black wrath and her magical skill. it is sirius who spends his life like a caged animal, slowly driven mad, angry, violent.
sirius never calls regulus a mamas boy because he knows if he did, regulus would know. his brother— the silent, quiet, perfect boy— is not walburga.
regulus is orion. the heart of the lion, and his father remade. when sirius criticizes him, it is not because he is violent, or cruel like their mother— it is because he does not act, and in sirius’s eyes, inaction is worse than anything else.
it’s not quite love that brings regulus to the cave. it’s not quite cowardice, or spite, either; he is a boy quite removed from such things. he is a boy who is indecisive and quiet, even if it masks a sharp wit and lovely laugh, a beautiful heart.
it’s bravery. it’s the memory of his brothers decision to walk out the door, and his choice every day not to come back. it’s the memory of his mother, choosing to overlook him all his life. the memories of his poor, weak father, who never made a choice for himself his whole life, and didn’t know how— didn’t know how to change fate, especially not his sons.
in the end, regulus was not made in the image of his mother or father. he was made in the image of his brother. always his brother.